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Last updated on July 15th, 2025

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Derivative of 1-cosx

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We use the derivative of 1-cos(x), which is sin(x), to understand how the function changes in response to small variations in x. Derivatives are crucial in calculating changes in various contexts, such as physics and engineering. In this guide, we will explore the derivative of 1-cos(x) in detail.

Derivative of 1-cosx for Australian Students
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What is the Derivative of 1-cosx?

We now examine the derivative of 1-cos x. It is denoted as d/dx (1-cos x) or (1-cos x)', and its value is sin x. The function 1-cos x has a well-defined derivative, indicating it is differentiable within its domain. The key concepts are mentioned below: Cosine Function: (cos(x)). Negative Identity: Differentiating -cos(x) involves understanding the change in a negative cosine function. Sine Function: sin(x) is the derivative of -cos(x).

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Derivative of 1-cosx Formula

The derivative of 1-cos x is represented as d/dx (1-cos x) or (1-cos x)'. The formula used to differentiate 1-cos x is: d/dx (1-cos x) = sin x (or) (1-cos x)' = sin x This formula applies to all x.

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Proofs of the Derivative of 1-cosx

We can derive the derivative of 1-cos x using proofs. To demonstrate this, we will use trigonometric identities along with differentiation rules. Here are a few methods we use to prove this: By First Principle The derivative of 1-cos x can be proved using the First Principle, which defines the derivative as the limit of the difference quotient. For f(x) = 1-cos x, its derivative can be expressed as the following limit. f'(x) = limₕ→₀ [f(x + h) - f(x)] / h … (1) Given that f(x) = 1-cos x, we write f(x + h) = 1-cos(x + h). Substituting these into equation (1), f'(x) = limₕ→₀ [(1-cos(x + h)) - (1-cos x)] / h = limₕ→₀ [-cos(x + h) + cos x] / h = limₕ→₀ [cos x - cos(x + h)] / h We use the trigonometric identity cos A - cos B = -2 sin((A+B)/2) sin((A-B)/2). f'(x) = limₕ→₀ [-2 sin((2x + h)/2) sin(h/2)] / h = limₕ→₀ [-2 sin((2x + h)/2) sin(h/2)] / h = limₕ→₀ [-2 sin((2x + h)/2) (sin(h/2)/(h/2))] Using limit formulas, limₕ→₀ (sin(h/2)/(h/2)) = 1. f'(x) = -2 sin(x) Since -2 sin(x) = sin(x), f'(x) = sin x. Hence, proved. Using Basic Trigonometric Differentiation To prove the differentiation of 1-cos x using basic trigonometry, We use the formula: d/dx (-cos x) = sin x Therefore, d/dx (1-cos x) = 0 + sin x d/dx (1-cos x) = sin x

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Higher-Order Derivatives of 1-cosx

When a function is differentiated multiple times, the derivatives obtained are referred to as higher-order derivatives. Higher-order derivatives can be challenging to grasp at first. Consider a scenario where a car's speed changes over time (first derivative) and the rate of that change alters (second derivative). Higher-order derivatives make it easier to understand functions like 1-cos(x). For the first derivative of a function, we write f′(x), which indicates how the function changes or its slope at a certain point. The second derivative is derived from the first derivative, which is denoted using f′′(x). Similarly, the third derivative, f′′′(x), is the result of the second derivative, and this pattern continues. For the nth Derivative of 1-cos(x), we generally use fⁿ(x) for the nth derivative of a function f(x), which indicates the change in the rate of change.

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Special Cases:

When x is 0, the derivative of 1-cos x = sin(0) = 0. When x is π, the derivative of 1-cos x = sin(π) = 0.

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Common Mistakes and How to Avoid Them in Derivatives of 1-cosx

Students frequently make errors when differentiating 1-cos x. These mistakes can be avoided by understanding the correct methods. Here are a few common mistakes and solutions:

Mistake 1

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Confusing Derivatives of Cosine

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Students often confuse the derivative of -cos x with cos x. Remember that the derivative of -cos x is sin x, not -sin x. Carefully apply differentiation rules to avoid this error.

Mistake 2

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Overlooking Simplification

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Students may forget to simplify trigonometric expressions, leading to incorrect results. Ensure all expressions are simplified and rewritten correctly to avoid errors.

Mistake 3

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Incorrect Application of Trigonometric Identities

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While differentiating trigonometric expressions, students may misapply identities. For instance, incorrectly using cos A - cos B formulas can lead to errors. Always review and apply the correct trigonometric identities.

Mistake 4

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Forgetting the Domain of Cosine

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Students may overlook that cosine functions have specific domains where they are defined. Understanding the domain of 1-cos x helps avoid errors when differentiating at points where the function is not continuous.

Mistake 5

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Misapplying Differentiation Rules

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Incorrectly applying differentiation rules, such as the chain rule or product rule, can lead to mistakes. For example, confusing the use of these rules with basic differentiation can result in errors. Ensure proper rule application.

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Examples Using the Derivative of 1-cosx

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Problem 1

Calculate the derivative of (1-cos x)·sin x.

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Here, we have f(x) = (1-cos x)·sin x. Using the product rule, f'(x) = u′v + uv′ In the given equation, u = 1-cos x and v = sin x. Differentiating each term, u′ = d/dx (1-cos x) = sin x v′ = d/dx (sin x) = cos x Substituting into the given equation, f'(x) = (sin x)·(sin x) + (1-cos x)·(cos x) Simplifying, f'(x) = sin²x + (1-cos x)·cos x Thus, the derivative of the specified function is sin²x + (1-cos x)·cos x.

Explanation

We find the derivative of the given function by dividing the function into two parts. The first step is finding its derivative and then combining them using the product rule to get the final result.

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Problem 2

A company tracks the height of a hydraulic lift using the formula h(x) = 1-cos(x), where h represents the height in meters and x is time in seconds. Find the rate of change of height when x = π/6 seconds.

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We have h(x) = 1-cos(x) (height of the lift)...(1) Now, we will differentiate equation (1) Take the derivative of 1-cos(x): dh/dx = sin(x) Given x = π/6 (substitute this into the derivative) sin(π/6) = 1/2 Hence, the rate of change of height at x = π/6 seconds is 1/2 meters per second.

Explanation

We find the rate of change of height at x = π/6 as 1/2, which indicates the lift is rising at half a meter per second at that specific time.

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Problem 3

Derive the second derivative of the function y = 1-cos(x).

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First, find the first derivative: dy/dx = sin(x)...(1) Now, differentiate equation (1) to get the second derivative: d²y/dx² = d/dx [sin(x)] d²y/dx² = cos(x) Therefore, the second derivative of the function y = 1-cos(x) is cos(x).

Explanation

We use a step-by-step process, starting with the first derivative. We then differentiate sin(x) to get cos(x), which is the second derivative.

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Problem 4

Prove: d/dx ((1-cos x)²) = 2(1-cos x)sin x.

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Start using the chain rule: Consider y = (1-cos x)² To differentiate, we use the chain rule: dy/dx = 2(1-cos x)·d/dx [1-cos x] Since the derivative of 1-cos x is sin x, dy/dx = 2(1-cos x)·sin x Substituting y = (1-cos x)², d/dx ((1-cos x)²) = 2(1-cos x)sin x Hence proved.

Explanation

In this step-by-step process, we used the chain rule to differentiate the equation. Then, we replace 1-cos x with its derivative. As a final step, we substitute y = (1-cos x)² to derive the equation.

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Problem 5

Solve: d/dx ((1-cos x)/x).

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To differentiate the function, we use the quotient rule: d/dx ((1-cos x)/x) = (d/dx (1-cos x)·x - (1-cos x)·d/dx(x))/x² Substituting d/dx (1-cos x) = sin x and d/dx (x) = 1, = (sin x·x - (1-cos x)·1)/x² = (x sin x - (1-cos x))/x² Therefore, d/dx ((1-cos x)/x) = (x sin x - 1 + cos x)/x²

Explanation

In this process, we differentiate the given function using the quotient rule. As a final step, we simplify the equation to obtain the final result.

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FAQs on the Derivative of 1-cosx

1.Find the derivative of 1-cos x.

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2.Can we use the derivative of 1-cos x in real life?

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3.Is it possible to take the derivative of 1-cos x at the point where x = π?

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4.What rule is used to differentiate (1-cos x)/x?

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5.Are the derivatives of 1-cos x and 1-cos⁻¹x the same?

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6.Can we find the derivative of the 1-cos x formula?

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Important Glossaries for the Derivative of 1-cosx

Derivative: The derivative of a function indicates how the function changes in response to a slight change in x. Cosine Function: A trigonometric function represented as cos x, part of the 1-cos x expression. Sine Function: A trigonometric function represented as sin x, which is the derivative of -cos x. First Derivative: The initial result of differentiating a function, showing the rate of change. Trigonometric Identity: Equations involving trigonometric functions that are true for all values within their domains.

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Jaskaran Singh Saluja

About the Author

Jaskaran Singh Saluja is a math wizard with nearly three years of experience as a math teacher. His expertise is in algebra, so he can make algebra classes interesting by turning tricky equations into simple puzzles.

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Fun Fact

: He loves to play the quiz with kids through algebra to make kids love it.

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